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Glossary
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Astigmatism
Astigmatism is the result of an inability of the eye to properly
focus an image onto the retina. The result is a blurred image.
Slight uncorrected astigmatism may not cause symptoms and may
not require correction.
Bifocal glasses
Bifocal glasses help you to see objects at a distance and up close.
This is done by having lenses in your glasses which contain two
different focusing powers (one that helps you to focus on objects
in the distance, and one that helps you to focus on up close).
Blepharitis
Blepharitis is inflammation of the eyelids, usually with redness,
swelling, and itching.
Cataract
A cataracts is a cloudiness or opacity of the crystalline lens
of the eye, which may cause a decrease in vision. Surgical removal
of the lens may be necessary if visual loss becomes significant,
with lost optical power replaced with an intraocular lens. Cataracts
may be congenital or caused by trauma, disease, or age.
Conjunctivitis (sometime called pink eye or red eye)
Conjunctivitis is inflammation or redness of the conjunctiva (a
thin, delicate membrane that covers the white part of the eye
and lines the eyelids).It can be caused by infection, allergies,
or physical agents like infrared or ultra-violet light. If caused
by infection, it can be transmitted to others by hand/eye contact.
Cornea
The cornea is the transparent front part of the eye through which
light enters through it. It is the window of the eye.
Crystalline lens
The crystalline lens is the eye's natural lens which assists in
focusing light onto the retina in the back of the eye.
Diabetic retinopathy
Diabetic retinopathy is damage to the retina due to diabetes which
may eventually lead to decreased vision and sometimes blindness.
Carefully controlling blood glucose levels is imperative. In many
cases it can be treated successfully with laser treatment.
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Farsightedness
(also referred to as hyperopia, hypermetropia or longsightedness)
Farsightedness is a condition of the eye in which vision is better
for distant objects than for near objects. It results from the
eyeball being too short from front to back, which causes light
to focus behind the retina rather than on the retina (see image).
Because the eye is unable to focus light onto the retina, images
appear blurry.
Glaucoma
Glaucoma is an eye disease characterized by damage to the optic
nerve (the nerve that sends information from the eye to your brain)
and reduction in field of vision. Most cases of glaucoma are related
to elevated intraocular pressure (which is the pressure inside
the eye), caused by problems with draining fluid inside the eyeball.
The first line of treatment is eye-drop/medication that decreases
the pressure inside the eye. In some cases eye surgery may be
required. Though glaucoma can lead to blindness, it can be successfully
treated if detected in the early stages.
Iris
The iris is the pigmented (colored) tissue lying behind the cornea
that gives the eye its color. It regulates the amount of light
entering the eye by varying the size of the pupil.
Lacrimal gland (also known as the tear gland)
The lacrimal gland is an almond-shaped structure that produces
tears. There is one lacrimal gland for each eyeball. It is located
above the eyeball, at the upper, outer region of the orbit (see
image).
Lens (also known as the crystalline lens)
The eye's natural lens is a transparent, biconvex intraocular
tissue that helps bring rays of light to a focus on the retina
(click here
to see the lens location in eye).
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Myopia
(also referred to as nearsightedness or short-sightedness)
Myopia is a visual defect in which distant objects appear blurred
because their images are focused in front of the retina rather
than on it. It results from the eyeball being too long from front
to back (see image).
Ophthalmologist
An ophthalmologist is a qualified medical doctor (MD) specializing
in diagnosis and treatment of refractive, medical and surgical
diseases and disorders.
Optician
An optician is a licensed professional who dispenses eyeglasses.
Optic nerve
The optic nerve is the largest sensory nerve of the eye. It transmits
visual information from the retina to the brain.
Optometrist
An optometrist is a professional (not an MD) who is licensed to
examine the eyes for visual defects, diagnose eye diseases or
impairments and prescribe treatment in some cases.
Pink eye (sometime called conjunctivitis or red eye)
Pink eye is inflammation or redness of the conjunctiva (a thin,
delicate membrane that covers the white part of the eyes and lines
the eyelids).It can be caused by infection, allergic reaction,
or physical agents like infrared or ultra-violet light. If caused
by infection, it can be transmitted to others by hand/eye contact.
Retina
The retina is light sensitive nerve tissue in the eye that converts
images from the eye's optical system into electrical impulses
that are sent along the optic nerve to the brain. It forms a thin
membranous lining in the back of the eye. (click here
to see the lens location in eye).
Sclera
The sclera is the white part of the eye. It is opaque, fibrous,
and protective. It surrounds the whole eyeball except for the
cornea at the front of the eye and the sheath covering the optic
nerve behind.
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Slit Lamp
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Slit Lamp
The slit lamp is an instrument consisting of a high-intensity
light source that can be focused to shine as a slit. The lamp
facilitates examination of the conjunctiva, cornea, crystalline
lens, eyelid, iris and sclera.
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Snellen chart
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Snellen chart
The Snellen chart is a chart used for assessing visual acuity.
Typically the chart contains rows of letters, numbers, or symbols
in standardized graded sizes, with a designated distance at which
each row should be legible to a normal eye.
Strabismus (squint)
Strabismus is a condition in which the eyes do not point in the
same direction. This is caused by unevenness in the muscles that
surround each eyeball.
Stye/Chalazion
A stye/chalazion is an infection or small abscess formation within
the glands on the edge of the eyelid.
Twenty-twenty
Twenty/twenty is considered normal visual acuity (visual acuity
refers to the ability to resolve two separated points or lines).
The first number is the standard distance (20 feet) between an
eye being tested and the test chart (containing letters, numbers
or symbols). The lower number indicates that a tested eye can
see the same small standard-sized letters or symbols as a normal
eye (at the standard distance of 20 feet).
Visual acuity
Visual acuity is an assessment of the eye's ability to distinguish
the details and shape of an object. Typically this is evaluated
by measuring the smallest identifiable object (letter, number
or symbol) that can be seen at a specified distance (usually the
standard distance of 20 ft).
Image
Licensing
Schematic representation of hypermetropia,
myopia, eye cross section.
Made by A. Baris Toprak MD. Vectorized by CryptWizard.
Image licence from Creative Commons. Licensing info here.
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